Touch-sensitive displays (also known as “touch screens” or “touchscreens”) are well known in the art. Touch screens are used in many electronic devices to display graphics and text, and to provide a user interface through which a user may interact with the devices. Touch screens are becoming more popular for use as displays and as user input devices on portable devices, such as mobile telephones and personal digital assistants (PDAs). The portable devices may be locked upon satisfaction of predefined lock conditions, such as upon manual locking by a user, and have to be unlocked in order to be used again. The portable devices with touch screens may be unlocked by any of several well-known unlocking procedures, such as pressing a predefined set of buttons (simultaneously or sequentially) or entering a code or password.